1. Field of the Invention
This invention pertains to a modular wall system useful for partitioning off and/or entirely defining subunits of a larger area. More particularly, the invention relates to a modular wall system wherein the enclosing structure can be assembled or disassembled in components, and wherein the assembled structure can be modified by removal of structural elements without affecting the remaining structure. The invention further pertains to a modular wall system wherein wall panels can be quickly assembled or disassembled, yet wherein the assembled wall system is capable of being sealed at the junctures of each attached wall panel to such a high degree that the wall system may be used as part of a cleanroom structure.
2. Prior Art
The present trend in construction of buildings used for manufacturing, office space, storage, and other business needs, is to build large floor areas having no walls or other means of closing off smaller units of the floor area. This allows the tenant to choose their own floor plan, and to fashion it through the use of modular wall systems. These wall systems include panels which can be fastened in place between the floor and ceiling at nearly any location across the larger floor area, to confine smaller sub-units useful for the purposes of the tenant. Since modular wall panels of this type are not required to carry any load of the building (i.e., are not load bearing walls), they need not remain permanently in their original location and can be removed, rearranged, or replaced depending on changing needs. U.S. Pat. Nos. 3,830,027 and 4,037,380 illustrate a modular construction which offers improved panel members, but does not provide the required sealing features which enable application as a cleanroom.
Prior art structures built for cleanroom use, have in the past been fabricated in accordance with permanent design features, as opposed to temporary or modular construction, because of the high risk and critical impact of microcontamination in certain types of manufacturing, (i.e. the production of integrated circuit chips, electronics components or other products which are subject to contamination in an environment of dust or other microcontamination).
The development of the portable, modular cleanroom enclosure has heretofore been deemed impractical for meeting the stringent requirements of these types of manufacturing environments. For example, the preparation of a multi-layered, integrated computer chip includes fabrication of wafer masks and layouts that include hundreds of tiny circuits whose operational condition depends on the absence of foreign materials. These chips are prepared in an industrial cleanroom which is classified by the maximum amount of contamination allowed in the form of airborne particles. For example, a Class 100 room at 0.05 microns means that a cubic foot of controlled airspace within the cleanroom will have no more than an average total of 100 particles no larger in size than 0.05 microns. Likewise, a Class 10 room means that there are only 10 or less particles of 0.05 microns in size or larger in a cubic foot of airspace.
The trends for increased productivity and chip capacity have increased the need for more stringent standards for cleanroom structures. Movements have developed to reduce the standard for measurement from 0.05 microns to 0.02 microns and to anticipate Class 1 cleanroom conditions. Also, the need to quickly and economically modify the cleanroom structure itself to changing usage requirements is also becoming more and more critical.
Although permanent structures were acceptable for earlier cleanrooms, modern industry demands greater structural adaptability. Many of these demands are not only a natural outgrowth of a changing technology in manufacturing, but also include long standing design problems unique to cleanroom production. For example, manufacturing equipment used within the cleanroom may require day to day maintenance while maintaining the cleanroom environmental requirements. Typically, equipment of this nature is installed as part of a service wall with the operational side of the equipment sealed to the interior of the cleanroom and the maintenance/access side exposed to a service isle exterior of the cleanroom.
Although repair work is facilitated by the service wall configuration, removal of machinery may involve modifications to the wall structure. Therefore, if equipment must be replaced, risk of damage to the cleanroom structure exists. Equally challenging is the need for an adapted wall structure which allows modification in configuration to permit change to new equipment as it is developed. Presently, progressive changes in equipment may require construction of a new cleanroom facility.
U.S. Pat. No. 4,667,579 to Daw shows a cleanroom structure including a plurality of fabricated wall studs removably attached at the junctures of panel elements in such a manner that sealing against particle infiltration is accomplished. This patent includes the use of a conventional steel stud which is slotted to receive a clip, wherein the mated clip is attachable to lateral flanges of abutting panel sections. Although this structure represents a significant improvement over prior art methods for construction of modular wall systems, it must be carefully assembled of the panels and support studs to avoid misalignment which would allow infiltration of dust and the like.
In a case of cleanroom construction, as opposed to other types of wall construction, careful construction techniques have traditionally been required to insure complete sealing of airflow through the wall. It would be a substantial improvement in the art if the structural components, specifically wall panels, were self adjusting to establish coalignment of panel sections within the single plane of panels, including complete sealing of all junctures, without the need or use of studs for supporting and/or fastening the panels.